// SPDX-License-Identifier: GPL-2.0
/*
* Architecture neutral utility routines for interacting with
* Hyper-V. This file is specifically for code that must be
* built-in to the kernel image when CONFIG_HYPERV is set
* (vs. being in a module) because it is called from architecture
* specific code under arch/.
*
* Copyright (C) 2021, Microsoft, Inc.
*
* Author : Michael Kelley <[email protected]>
*/
#include <linux/types.h>
#include <linux/acpi.h>
#include <linux/export.h>
#include <linux/bitfield.h>
#include <linux/cpumask.h>
#include <linux/sched/task_stack.h>
#include <linux/panic_notifier.h>
#include <linux/ptrace.h>
#include <linux/random.h>
#include <linux/efi.h>
#include <linux/kdebug.h>
#include <linux/kmsg_dump.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/dma-map-ops.h>
#include <linux/set_memory.h>
#include <asm/hyperv-tlfs.h>
#include <asm/mshyperv.h>
/*
* hv_root_partition, ms_hyperv and hv_nested are defined here with other
* Hyper-V specific globals so they are shared across all architectures and are
* built only when CONFIG_HYPERV is defined. But on x86,
* ms_hyperv_init_platform() is built even when CONFIG_HYPERV is not
* defined, and it uses these three variables. So mark them as __weak
* here, allowing for an overriding definition in the module containing
* ms_hyperv_init_platform().
*/
bool __weak hv_root_partition;
EXPORT_SYMBOL_GPL(hv_root_partition);
bool __weak hv_nested;
EXPORT_SYMBOL_GPL(hv_nested);
struct ms_hyperv_info __weak ms_hyperv;
EXPORT_SYMBOL_GPL(ms_hyperv);
u32 *hv_vp_index;
EXPORT_SYMBOL_GPL(hv_vp_index);
u32 hv_max_vp_index;
EXPORT_SYMBOL_GPL(hv_max_vp_index);
void * __percpu *hyperv_pcpu_input_arg;
EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
void * __percpu *hyperv_pcpu_output_arg;
EXPORT_SYMBOL_GPL(hyperv_pcpu_output_arg);
static void hv_kmsg_dump_unregister(void);
static struct ctl_table_header *hv_ctl_table_hdr;
/*
* Hyper-V specific initialization and shutdown code that is
* common across all architectures. Called from architecture
* specific initialization functions.
*/
void __init hv_common_free(void)
{
unregister_sysctl_table(hv_ctl_table_hdr);
hv_ctl_table_hdr = NULL;
if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
hv_kmsg_dump_unregister();
kfree(hv_vp_index);
hv_vp_index = NULL;
free_percpu(hyperv_pcpu_output_arg);
hyperv_pcpu_output_arg = NULL;
free_percpu(hyperv_pcpu_input_arg);
hyperv_pcpu_input_arg = NULL;
}
/*
* Functions for allocating and freeing memory with size and
* alignment HV_HYP_PAGE_SIZE. These functions are needed because
* the guest page size may not be the same as the Hyper-V page
* size. We depend upon kmalloc() aligning power-of-two size
* allocations to the allocation size boundary, so that the
* allocated memory appears to Hyper-V as a page of the size
* it expects.
*/
void *hv_alloc_hyperv_page(void)
{
BUILD_BUG_ON(PAGE_SIZE < HV_HYP_PAGE_SIZE);
if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
return (void *)__get_free_page(GFP_KERNEL);
else
return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
void *hv_alloc_hyperv_zeroed_page(void)
{
if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
else
return kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(hv_alloc_hyperv_zeroed_page);
void hv_free_hyperv_page(void *addr)
{
if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
free_page((unsigned long)addr);
else
kfree(addr);
}
EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
static void *hv_panic_page;
/*
* Boolean to control whether to report panic messages over Hyper-V.
*
* It can be set via /proc/sys/kernel/hyperv_record_panic_msg
*/
static int sysctl_record_panic_msg = 1;
/*
* sysctl option to allow the user to control whether kmsg data should be
* reported to Hyper-V on panic.
*/
static struct ctl_table hv_ctl_table[] = {
{
.procname = "hyperv_record_panic_msg",
.data = &sysctl_record_panic_msg,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE
},
};
static int hv_die_panic_notify_crash(struct notifier_block *self,
unsigned long val, void *args);
static struct notifier_block hyperv_die_report_block = {
.notifier_call = hv_die_panic_notify_crash,
};
static struct notifier_block hyperv_panic_report_block = {
.notifier_call = hv_die_panic_notify_crash,
};
/*
* The following callback works both as die and panic notifier; its
* goal is to provide panic information to the hypervisor unless the
* kmsg dumper is used [see hv_kmsg_dump()], which provides more
* information but isn't always available.
*
* Notice that both the panic/die report notifiers are registered only
* if we have the capability HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE set.
*/
static int hv_die_panic_notify_crash(struct notifier_block *self,
unsigned long val, void *args)
{
struct pt_regs *regs;
bool is_die;
/* Don't notify Hyper-V unless we have a die oops event or panic. */
if (self == &hyperv_panic_report_block) {
is_die = false;
regs = current_pt_regs();
} else { /* die event */
if (val != DIE_OOPS)
return NOTIFY_DONE;
is_die = true;
regs = ((struct die_args *)args)->regs;
}
/*
* Hyper-V should be notified only once about a panic/die. If we will
* be calling hv_kmsg_dump() later with kmsg data, don't do the
* notification here.
*/
if (!sysctl_record_panic_msg || !hv_panic_page)
hyperv_report_panic(regs, val, is_die);
return NOTIFY_DONE;
}
/*
* Callback from kmsg_dump. Grab as much as possible from the end of the kmsg
* buffer and call into Hyper-V to transfer the data.
*/
static void hv_kmsg_dump(struct kmsg_dumper *dumper,
struct kmsg_dump_detail *detail)
{
struct kmsg_dump_iter iter;
size_t bytes_written;
/* We are only interested in panics. */
if (detail->reason != KMSG_DUMP_PANIC || !sysctl_record_panic_msg)
return;
/*
* Write dump contents to the page. No need to synchronize; panic should
* be single-threaded.
*/
kmsg_dump_rewind(&iter);
kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE,
&bytes_written);
if (!bytes_written)
return;
/*
* P3 to contain the physical address of the panic page & P4 to
* contain the size of the panic data in that page. Rest of the
* registers are no-op when the NOTIFY_MSG flag is set.
*/
hv_set_msr(HV_MSR_CRASH_P0, 0);
hv_set_msr(HV_MSR_CRASH_P1, 0);
hv_set_msr(HV_MSR_CRASH_P2, 0);
hv_set_msr(HV_MSR_CRASH_P3, virt_to_phys(hv_panic_page));
hv_set_msr(HV_MSR_CRASH_P4, bytes_written);
/*
* Let Hyper-V know there is crash data available along with
* the panic message.
*/
hv_set_msr(HV_MSR_CRASH_CTL,
(HV_CRASH_CTL_CRASH_NOTIFY |
HV_CRASH_CTL_CRASH_NOTIFY_MSG));
}
static struct kmsg_dumper hv_kmsg_dumper = {
.dump = hv_kmsg_dump,
};
static void hv_kmsg_dump_unregister(void)
{
kmsg_dump_unregister(&hv_kmsg_dumper);
unregister_die_notifier(&hyperv_die_report_block);
atomic_notifier_chain_unregister(&panic_notifier_list,
&hyperv_panic_report_block);
hv_free_hyperv_page(hv_panic_page);
hv_panic_page = NULL;
}
static void hv_kmsg_dump_register(void)
{
int ret;
hv_panic_page = hv_alloc_hyperv_zeroed_page();
if (!hv_panic_page) {
pr_err("Hyper-V: panic message page memory allocation failed\n");
return;
}
ret = kmsg_dump_register(&hv_kmsg_dumper);
if (ret) {
pr_err("Hyper-V: kmsg dump register error 0x%x\n", ret);
hv_free_hyperv_page(hv_panic_page);
hv_panic_page = NULL;
}
}
int __init hv_common_init(void)
{
int i;
union hv_hypervisor_version_info version;
/* Get information about the Hyper-V host version */
if (!hv_get_hypervisor_version(&version))
pr_info("Hyper-V: Host Build %d.%d.%d.%d-%d-%d\n",
version.major_version, version.minor_version,
version.build_number, version.service_number,
version.service_pack, version.service_branch);
if (hv_is_isolation_supported())
sysctl_record_panic_msg = 0;
/*
* Hyper-V expects to get crash register data or kmsg when
* crash enlightment is available and system crashes. Set
* crash_kexec_post_notifiers to be true to make sure that
* calling crash enlightment interface before running kdump
* kernel.
*/
if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
u64 hyperv_crash_ctl;
crash_kexec_post_notifiers = true;
pr_info("Hyper-V: enabling crash_kexec_post_notifiers\n");
/*
* Panic message recording (sysctl_record_panic_msg)
* is enabled by default in non-isolated guests and
* disabled by default in isolated guests; the panic
* message recording won't be available in isolated
* guests should the following registration fail.
*/
hv_ctl_table_hdr = register_sysctl("kernel", hv_ctl_table);
if (!hv_ctl_table_hdr)
pr_err("Hyper-V: sysctl table register error");
/*
* Register for panic kmsg callback only if the right
* capability is supported by the hypervisor.
*/
hyperv_crash_ctl = hv_get_msr(HV_MSR_CRASH_CTL);
if (hyperv_crash_ctl & HV_CRASH_CTL_CRASH_NOTIFY_MSG)
hv_kmsg_dump_register();
register_die_notifier(&hyperv_die_report_block);
atomic_notifier_chain_register(&panic_notifier_list,
&hyperv_panic_report_block);
}
/*
* Allocate the per-CPU state for the hypercall input arg.
* If this allocation fails, we will not be able to setup
* (per-CPU) hypercall input page and thus this failure is
* fatal on Hyper-V.
*/
hyperv_pcpu_input_arg = alloc_percpu(void *);
BUG_ON(!hyperv_pcpu_input_arg);
/* Allocate the per-CPU state for output arg for root */
if (hv_root_partition) {
hyperv_pcpu_output_arg = alloc_percpu(void *);
BUG_ON(!hyperv_pcpu_output_arg);
}
hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
GFP_KERNEL);
if (!hv_vp_index) {
hv_common_free();
return -ENOMEM;
}
for (i = 0; i < num_possible_cpus(); i++)
hv_vp_index[i] = VP_INVAL;
return 0;
}
void __init ms_hyperv_late_init(void)
{
struct acpi_table_header *header;
acpi_status status;
u8 *randomdata;
u32 length, i;
/*
* Seed the Linux random number generator with entropy provided by
* the Hyper-V host in ACPI table OEM0.
*/
if (!IS_ENABLED(CONFIG_ACPI))
return;
status = acpi_get_table("OEM0", 0, &header);
if (ACPI_FAILURE(status) || !header)
return;
/*
* Since the "OEM0" table name is for OEM specific usage, verify
* that what we're seeing purports to be from Microsoft.
*/
if (strncmp(header->oem_table_id, "MICROSFT", 8))
goto error;
/*
* Ensure the length is reasonable. Requiring at least 8 bytes and
* no more than 4K bytes is somewhat arbitrary and just protects
* against a malformed table. Hyper-V currently provides 64 bytes,
* but allow for a change in a later version.
*/
if (header->length < sizeof(*header) + 8 ||
header->length > sizeof(*header) + SZ_4K)
goto error;
length = header->length - sizeof(*header);
randomdata = (u8 *)(header + 1);
pr_debug("Hyper-V: Seeding rng with %d random bytes from ACPI table OEM0\n",
length);
add_bootloader_randomness(randomdata, length);
/*
* To prevent the seed data from being visible in /sys/firmware/acpi,
* zero out the random data in the ACPI table and fixup the checksum.
* The zero'ing is done out of an abundance of caution in avoiding
* potential security risks to the rng. Similarly, reset the table
* length to just the header size so that a subsequent kexec doesn't
* try to use the zero'ed out random data.
*/
for (i = 0; i < length; i++) {
header->checksum += randomdata[i];
randomdata[i] = 0;
}
for (i = 0; i < sizeof(header->length); i++)
header->checksum += ((u8 *)&header->length)[i];
header->length = sizeof(*header);
for (i = 0; i < sizeof(header->length); i++)
header->checksum -= ((u8 *)&header->length)[i];
error:
acpi_put_table(header);
}
/*
* Hyper-V specific initialization and die code for
* individual CPUs that is common across all architectures.
* Called by the CPU hotplug mechanism.
*/
int hv_common_cpu_init(unsigned int cpu)
{
void **inputarg, **outputarg;
u64 msr_vp_index;
gfp_t flags;
int pgcount = hv_root_partition ? 2 : 1;
void *mem;
int ret;
/* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
flags = irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL;
inputarg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
/*
* hyperv_pcpu_input_arg and hyperv_pcpu_output_arg memory is already
* allocated if this CPU was previously online and then taken offline
*/
if (!*inputarg) {
mem = kmalloc(pgcount * HV_HYP_PAGE_SIZE, flags);
if (!mem)
return -ENOMEM;
if (hv_root_partition) {
outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
*outputarg = (char *)mem + HV_HYP_PAGE_SIZE;
}
if (!ms_hyperv.paravisor_present &&
(hv_isolation_type_snp() || hv_isolation_type_tdx())) {
ret = set_memory_decrypted((unsigned long)mem, pgcount);
if (ret) {
/* It may be unsafe to free 'mem' */
return ret;
}
memset(mem, 0x00, pgcount * HV_HYP_PAGE_SIZE);
}
/*
* In a fully enlightened TDX/SNP VM with more than 64 VPs, if
* hyperv_pcpu_input_arg is not NULL, set_memory_decrypted() ->
* ... -> cpa_flush()-> ... -> __send_ipi_mask_ex() tries to
* use hyperv_pcpu_input_arg as the hypercall input page, which
* must be a decrypted page in such a VM, but the page is still
* encrypted before set_memory_decrypted() returns. Fix this by
* setting *inputarg after the above set_memory_decrypted(): if
* hyperv_pcpu_input_arg is NULL, __send_ipi_mask_ex() returns
* HV_STATUS_INVALID_PARAMETER immediately, and the function
* hv_send_ipi_mask() falls back to orig_apic.send_IPI_mask(),
* which may be slightly slower than the hypercall, but still
* works correctly in such a VM.
*/
*inputarg = mem;
}
msr_vp_index = hv_get_msr(HV_MSR_VP_INDEX);
hv_vp_index[cpu] = msr_vp_index;
if (msr_vp_index > hv_max_vp_index)
hv_max_vp_index = msr_vp_index;
return 0;
}
int hv_common_cpu_die(unsigned int cpu)
{
/*
* The hyperv_pcpu_input_arg and hyperv_pcpu_output_arg memory
* is not freed when the CPU goes offline as the hyperv_pcpu_input_arg
* may be used by the Hyper-V vPCI driver in reassigning interrupts
* as part of the offlining process. The interrupt reassignment
* happens *after* the CPUHP_AP_HYPERV_ONLINE state has run and
* called this function.
*
* If a previously offlined CPU is brought back online again, the
* originally allocated memory is reused in hv_common_cpu_init().
*/
return 0;
}
/* Bit mask of the extended capability to query: see HV_EXT_CAPABILITY_xxx */
bool hv_query_ext_cap(u64 cap_query)
{
/*
* The address of the 'hv_extended_cap' variable will be used as an
* output parameter to the hypercall below and so it should be
* compatible with 'virt_to_phys'. Which means, it's address should be
* directly mapped. Use 'static' to keep it compatible; stack variables
* can be virtually mapped, making them incompatible with
* 'virt_to_phys'.
* Hypercall input/output addresses should also be 8-byte aligned.
*/
static u64 hv_extended_cap __aligned(8);
static bool hv_extended_cap_queried;
u64 status;
/*
* Querying extended capabilities is an extended hypercall. Check if the
* partition supports extended hypercall, first.
*/
if (!(ms_hyperv.priv_high & HV_ENABLE_EXTENDED_HYPERCALLS))
return false;
/* Extended capabilities do not change at runtime. */
if (hv_extended_cap_queried)
return hv_extended_cap & cap_query;
status = hv_do_hypercall(HV_EXT_CALL_QUERY_CAPABILITIES, NULL,
&hv_extended_cap);
/*
* The query extended capabilities hypercall should not fail under
* any normal circumstances. Avoid repeatedly making the hypercall, on
* error.
*/
hv_extended_cap_queried = true;
if (!hv_result_success(status)) {
pr_err("Hyper-V: Extended query capabilities hypercall failed 0x%llx\n",
status);
return false;
}
return hv_extended_cap & cap_query;
}
EXPORT_SYMBOL_GPL(hv_query_ext_cap);
void hv_setup_dma_ops(struct device *dev, bool coherent)
{
arch_setup_dma_ops(dev, coherent);
}
EXPORT_SYMBOL_GPL(hv_setup_dma_ops);
bool hv_is_hibernation_supported(void)
{
return !hv_root_partition && acpi_sleep_state_supported(ACPI_STATE_S4);
}
EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
/*
* Default function to read the Hyper-V reference counter, independent
* of whether Hyper-V enlightened clocks/timers are being used. But on
* architectures where it is used, Hyper-V enlightenment code in
* hyperv_timer.c may override this function.
*/
static u64 __hv_read_ref_counter(void)
{
return hv_get_msr(HV_MSR_TIME_REF_COUNT);
}
u64 (*hv_read_reference_counter)(void) = __hv_read_ref_counter;
EXPORT_SYMBOL_GPL(hv_read_reference_counter);
/* These __weak functions provide default "no-op" behavior and
* may be overridden by architecture specific versions. Architectures
* for which the default "no-op" behavior is sufficient can leave
* them unimplemented and not be cluttered with a bunch of stub
* functions in arch-specific code.
*/
bool __weak hv_is_isolation_supported(void)
{
return false;
}
EXPORT_SYMBOL_GPL(hv_is_isolation_supported);
bool __weak hv_isolation_type_snp(void)
{
return false;
}
EXPORT_SYMBOL_GPL(hv_isolation_type_snp);
bool __weak hv_isolation_type_tdx(void)
{
return false;
}
EXPORT_SYMBOL_GPL(hv_isolation_type_tdx);
void __weak hv_setup_vmbus_handler(void (*handler)(void))
{
}
EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
void __weak hv_remove_vmbus_handler(void)
{
}
EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
void __weak hv_setup_kexec_handler(void (*handler)(void))
{
}
EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
void __weak hv_remove_kexec_handler(void)
{
}
EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
void __weak hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
{
}
EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
void __weak hv_remove_crash_handler(void)
{
}
EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
void __weak hyperv_cleanup(void)
{
}
EXPORT_SYMBOL_GPL(hyperv_cleanup);
u64 __weak hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
{
return HV_STATUS_INVALID_PARAMETER;
}
EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
u64 __weak hv_tdx_hypercall(u64 control, u64 param1, u64 param2)
{
return HV_STATUS_INVALID_PARAMETER;
}
EXPORT_SYMBOL_GPL(hv_tdx_hypercall);
Codebase Browser
linux